Balanced slide-valve



(No Model.)

J. W. STOKES.

BALANCED SLIDE VALVE. No. 342,763. Patented May 25, 1886,

' INVENTOB:

BY Maud m4,

Among s.

NITED STATES PATENT OFFICE.

JOHN XV. STOKES, OF PANA, ILLINOIS.

BALANCED SLIDE-VALV'E.

SPECIFICATION forming part of Letters Patent No. 342,763, dated May 25,1886.

Application filed February 6, lBG. Serial No. 191,005. (No model.)

To all whom it mayconcern:

Be it known that I, JOHN \V. STOKES, of Pana, county of Christian, andState of Illinois, have invented a new and Improved BalancedSlide-Valve, of which the following is afull, clear, and exactdescription.

. The object of my invention is to provide a new and improvedslide-valve, which is perfeet] y balanced by being held in contact withthe balancing-plate on the steam chest lid without the aid of springswhen steam-pressure is applied.

The invention consists of a slide-valve pro vided withvertically-sliding bars, forming a frame fitted in grooves on top of theslide-valve, which frame is moved to and held in contact with the underside of the balancing-plate on the steanrchest cover or lid by thepressure of the live steam.

The invention also consists of various parts and details andcombinations of the same, as will be fully described hereinafter.

Reference is to be had to the accompanying drawings, forming a part ofthis specification, in which similar letters of reference indicatecorresponding parts in all the figures.

Figure 1 is a cross-sectional view of the steam-chest provided with myimproved balancing slide-valve, which is shown partly in section. Fig. 2is a plan view of the slidevalve. Fig. 3 is a sectional elevation of thesteam-chest provided with my improved valve, which is shown partly insection.

Heretofore the balancing of slide-valves has been accomplished bycircular disks held in contact with the steam-chest cover, or bystraight strips with springs, held similarly by means of the springs;but the circular disks soon wear out of true, so as to allow the livesteam to leak into the exhaust, and the straight strips supported by thesprings lose their respective posit-ions in relationto the valve, andare continually in contact with the cover of the steam-chest, therebycreating unnecessary friction and wear, and are liable, when the steamis shut off, to draw cinders into the cylinders and steam-chest, therebymaking asupplementary air-valve necessary.

My improved balanced slide-valve will wear evenly, thereby giving longservice, and will close automatically when steam-pressure is applied.When the steam-pressure is withdrawn, the balancing-frame of theslide-valve is out of contact with the balancing-plate attached to thesteam-chest cover.

The slide-valve A is provided on top with apertures B,which lead intothe exhaust-cavity G of the slide-valve. The top of the slidevalve A isprovided near its outer edges with grooves D,which extend around thesaid edges of the valve. In these grooves D are placed the sliding barsE, provided on their inner edges with flanges E, and on their outeredges with curved projections E". The sliding bars E, of which there arefour-one on each sideform a complete frame of rectangular or other form,and which is placed a little below the under side of a balancing-plate,F, attached to the lid G of the steam-chest H. The inner flanges, E, ofthe sliding bars E rest usually on the top of the slide-valve A. Whenthe full pressure of steam is applied to the steamchest H, the currentof steam seeks to rush into the space formed between the balancingpl'ateF and the sliding bars E, and into the cavity 0 by means of the holes13, thereby forcing the sliding bars E upward by pressing against thecurved flanges E until the sliding bars rest against the under surfaceof the balancing-plate F, so that the steam is prevented from enteringthe exhaust-cavity 0 through the apertures B. As soon as thesteam-pressure is withdrawn, the sliding bars E slide downward to theirnormal positions by their own weight, so that the sliding valve Ais notin contact with the balancing-plate F when no pressure is applied, butis onl'yin contact when under pressure.

The balancing-plate F may be entirely dis pensed with, the cover G beingused instead, by being placed a short distance above the top edge of thesliding bars E.

It will be seen that there is free communication between the interior ofthe steam-chest H and the eXhaust-cavityOaslong as no pressure isapplied by means of the aperturesBin thetop of the slide-valve A, andthe space between the balance-plate and the frame, thereby avoiding thenecessity of a supplementary relief air'valve, to prevent cinders frombeing drawn into the cylinders and steam-chest.

It will be understood that the outer projecting flanges, E on thesliding bars E permit the steam'to. lift the "sliding bars E into con.tact with the balancing-plate F.

Having thus fully described my invention,

2. The slide-valve A, having the apertures B, leading into theexhaust-cavity O, and the sliding bars E, forming a frame, and providedI claim as new and desire to secure by Letters 1 with the inner flanges,E, and the outer curved Patent-- v 1. A sliding valve, A, provided withaperturw B, leading into the exhaust-cavity C, and having the grooves D,in combination with the sliding bars E, sliding in the grooves D, and

provided with the inner flanges or stops, E,

and the outer curved projections, E", substantially as herein shown anddescribed.

projections, E in combination with the baiancing-plate F, attached tothe cover or lid G of the steam-chest H, substantiallyas herein shownand described.

JOHN \V. STOKES. Witnesses:

A. S. PHILLIPS, J. O. YOUNG.

